1. Field of the Invention
The present invention relates to a turret for a machine tool in which at least one rotating tool is mounted on the turret and this rotating tool is rotated for machining a workpiece.
2. Description of the Related Art
In, for example, a lathe out of machine tools, a single or a plurality of rotating tools are mounted on a turret, and the rotating tool is rotated by a rotational driving motor and machines a workpiece. In such a lathe, a swivel portion is provided on a head portion of the turret. The plurality of tools such as rotating tools or other tools are mounted radially on this swivel portion.
The swivel portion makes a swiveling motion so that a desired rotating tool or another tool is indexed at an index position. When the rotating tool is indexed, the rotating tool is rotated by the rotational driving motor. For this reason, a driving force (running torque) of the rotational driving motor is transmitted to the rotating tool by a power transmission mechanism having a belt, a bevel gear, a bearing or the like.
For example, Japanese Patent Application Laid-Open No. 2003-251505 describes a turret for rotating tools of a lathe in which a driving force of a rotational driving motor is transmitted to the rotating tool by bevel gears or the like. An interior of a swivel portion of the rotating tool turret is hollow. The bevel gears, bearings and the like of a power transmission mechanism are incorporated in this hollow space.
In the above-described conventional lathe or the lathe described in Japanese Patent Application Laid-Open No. 2003-251505, a rotational driving motor is arranged at a place remote from the rotating tools.
Accordingly, a structure of the power transmission mechanism for rotating the tool is complicated. Heat and vibration are generated from the belts, bevel gears, bearings and the like of the power transmission mechanism. As a result, an energy loss occurs so that the power transmission efficiency degrades and noise is also generated.